I found the perfect free lens cap that does not bump into the cap when you turn it on. It fits perfectly. Who says prunes aren't good for you!! The top of Sunsweet Ones. Look for it in the dried fruit section.

A "Sweet" find. I can't decide if I want to leave it as is or do a little creative painting. All it really needs is a small hole drilled in the edge for the nylon "string". I'm sure it's going to get "regular" use.

I finally finished the prunes. But I found a better "no bump" lens cap. The Sweet Ones top works well if you do not want the "hood ring" adapter left on.
I painted it flat black. That's the first picture.

Picture 2
However, if you want to keep it in place, the top of a Rust-oleum spray paint top works great. Cut it about an inch from the top. Clean out the ribs on the inside (Dremel tool works great). Now you have a no bump lens cap.

The Great Stuff foam cap worked pretty good also. But it needs to be lined with electrical tape to make the fit tighter.